NOVEL BISPECIFIC IMMUNOPROBE FOR RAPID AND SENSITIVE DETECTION OF PROSTATE-SPECIFIC ANTIGEN

Prostate-specific antigen (PSA) is one of the most useful tumor marker s for the screening and follow-up of prostate cancer. Bispecific monoc lonal antibodies (bsMAbs) are unique immunoprobes that incorporate two different binding sites in the same antibody molecule. This antibody designing can bring important advantages in the development of new imm unoassays. We have developed a new hybrid hybridoma that secretes bsMA b anti-PSA x anti-horseradish peroxidase. This bsMAb has shown rapid k inetics and an excellent detection limit in a sandwich single-step ass ay with a total incubation time of 15 min and a 5-min substrate develo pment. This assay in a manual format has a detection limit of 0.028 mu g/L. Comparison with the Hybritech Tandem-E(R) PSA assay yielded a re gression equation with slope = 0.433 [95% confidence interval (CI) 0.4 15-0.451], intercept = 0.88 (CI = 0.45-1.31), and S-y\x = 1.83 mu g/L, (r = 0.98). This new immunoprobe can be used to develop a new generat ion of assays for clinical laboratories and can be adapted to screenin g devices for physicians' offices and even home diagnostics.